MOCVD processes using precursors based on organometalloid ligands

ABSTRACT

Chemical vapor deposition processes utilize as precursors volatile metal complexes with ligands containing metalloid elements silicon, germanium, tin or lead.

FIELD OF INVENTION

This invention relates to chemical vapor deposition processes utilizingorganometalloid compounds and metal complexes thereof.

BACKGROUND OF THE INVENTION

As the microelectronics industry moves into ultralarge scale integration(ULSI), enhancement in performance speeds of integrated circuits will beachieved by reducing the device feature size and thereby the overall diesize. As a result, density constraints will require multilevelstructures with vertical interconnects. It is expected that the use ofmetals with lower resistivity, such as gold, silver and especiallycopper, will be necessary because of the submicron geometries.

Fabrication of interconnect structures includes one or moremetallization steps. Metallization is commonly accomplished by physicalvapor deposition (PVD) processes, including evaporating and sputtering.Chemical vapor deposition (CVD) processes have an advantage over theseso-called "line of sight" processes in the fabrication of submicronvertical interconnects because conformal layers of metals are moreeasily produced.

In CVD, a volatile precursor, usually a complex of a metal with anorganic ligand, serves as a source of the metal. The precursor isdelivered to the substrate in the vapor phase and decomposed on thesurface to release the metal. The precursor must exhibit sufficientthermal stability to prevent premature degradation or contamination ofthe substrate and at the same time facilitate easy handling. Vaporpressure, the adsorption/desorption behaviour, the chemical reactionpathways, the decomposition temperature can directly affect the purityof the deposited metal film and the rate of thin-film formation.

CVD precursors very frequently are based on complexes of metals withβ-diketonates such as 2,2,6,6-tetramethyl-3,5-heptanedione (thd) andacetylacetonate (acac) and fluorinated β-diketonates, such as1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hfa or hfac) and2,2-diethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (fod). Volatilityof the non-fluorinated precursors is insufficient for many applications.The fluorinated analogs possess greater volatility, but also have atendency to fragment, a consequence of fluorinemigration/carbon-fluorine bond cleavage at elevated temperatures,leading to contamination of the substrate. Consequently, a need existsfor precursors which retain volatility yet release the metal withoutdegradation of the ligand and for ligands which are not labile ordisposed toward fragmentation.

It is therefore an object of this invention to develop metal complexesfor CVD precursors that are highly volatile and yet stable at thesublimation point and also retain desirable processing features. It is afurther object to develop ligands for use in CVD precursors which caninduce high volatility in a metal and can release the metal withoutdegradation of the ligand. It is a further object to provide newsynthetic routes for the synthesis of these ligands from commerciallyavailable starting materials in good yields.

SUMMARY OF THE INVENTION

It has been surprisingly discovered that certain organic compoundscontaining silicon, germanium, tin or lead, when complexed with a metal,can induce high volatility in the metal complex. The resulting complexesare stable at the sublimation point and retain desirable processingfeatures. The compounds have the structure of formula I: ##STR1##wherein R¹ is C₂ or higher alkyl, substituted alkyl, haloalkyl,cycloalkyl, C₇ or higher aryl, substituted aryl, heteroaryl, arylalkyl,alkoxy, acyl, alkyl carboxylate, aryl carboxylate, alkenyl, alkynyl, or

E² (R⁶)(R⁷)(R⁸);

R² is H, halogen, nitro, or haloalkyl;

E¹ and E² are independently Si, Ge, Sn, or Pb;

R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently chosen from alkyl,substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl,alkoxy, alkenyl, alkynyl or R⁴ and R⁵, or R⁷ and R⁸ taken together forma divalent alkyl radical;

Y and Z are independently O, S or NR⁹ ; and

R⁹ is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.

The present invention also relates to metal-ligand complexes that arehighly volatile and yet stable at the sublimation point. The complexesalso retain desirable processing features. The metal complexes of thepresent invention have the structure of formula II:

    ML.sub.n ·pD                                      (II)

wherein

M is a metal chosen from the group consisting of: Li, Na, K, Rb, Cs, Mg,Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, Mo, W, Mn,Re, Sm, Fe, Ru, Eu, Os, Co, Rh, Ir, Gd, Ni, Pd, Pt, Tb, Cu, Ag, Au, Dy,Ho, Al, Ga, In, Tl, Er, Ge, Sn, Pb, Tm, Sb, Bi, Yb, and Lu;

D is a neutral coordinating ligand;

n is equal to the valence of M;

p is zero or an integer from 1 to 6; and

L is a compound of formula III: ##STR2## wherein R¹ is alkyl,substituted alkyl, haloalkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, acyl, alkyl carboxylate, arylcarboxylate, alkenyl, alkynyl, or E² (R⁶)(R⁷)(R⁸);

R² is H, halogen, nitro, or haloalkyl;

E¹ and E² are independently Si, Ge, Sn, or Pb;

R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently chosen from alkyl,substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl,alkoxy, alkenyl, alkynyl or R⁴ and R⁵, or R⁷ and R⁸ taken together formna divalent alkyl radical; Y and Z are independently O, S or NR⁹ ; and

R⁹ is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.

In another aspect, the present invention relates to a method ofdepositing a metal-containing layer on a substrate comprising vaporizinga metal-ligand complex of formula II and decomposing the metal-ligandcomplex in the presence of the substrate.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to organometalloid compounds that confervolatility on a metal when complexed therewith. Metalloids are definedherein as the elements silicon, germanium, tin and lead.Organometalloids are compounds containing one or more metalloid atomsbonded to a carbon atom. The organo-metalloid compounds of the presentinvention have the structure of formula I: ##STR3## wherein R¹ is C₂ orhigher alkyl, substituted alkyl, haloalkyl, cycloalkyl, C₇ or higheraryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, acyl, alkylcarboxylate, aryl carboxylate, alkenyl, alkynyl, or E² (R⁶)(R⁷)(R⁸);

R² is H, halogen, nitro, or haloalkyl;

E¹ and E² are independently Si, Ge, Sn, or Pb;

R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently chosen from alkyl,substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl,alkoxy, alkenyl, alkynyl or R⁴ and R⁵, or R⁷ and R⁸ taken together forma divalent alkyl radical;

Y and Z are independently O, S or NR⁹ ; and

R⁹ is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.

In a preferred embodiment, I is a silyl β-diketonate or a silylβ-thioketonate and R¹ is C₂ or higher alkyl, C₇ or higher aryl, orhaloalkyl; R² is H; R³, R⁴, and R⁵ are methyl; E¹ is Si; and Y and Z areindependently O or S.

In a more preferred embodiment, R¹ is ethyl, isopropyl, n-propyl,isobutyl, n-butyl, t-butyl, trifluoromethyl, heptafluoropropyl,2-propenyl or phenyl; E¹ is Si; and Y and Z are O or Y is S and Z is O.

In an even more preferred embodiment the compound is one of thoseappearing in Table 1:

                                      TABLE 1                                     __________________________________________________________________________     ##STR4##                                                                                         ##STR5##                                                   ##STR6##                                                                                         ##STR7##                                                   ##STR8##                                                                                         ##STR9##                                                   ##STR10##                                                                                        ##STR11##                                                  ##STR12##                                                                                        ##STR13##                                                 __________________________________________________________________________

The volatile metal complexes of the present invention are useful inprocesses which deposit a metal on substrate from a vapor phase, such asmetal organic chemical vapor deposition (MOCVD) , molecular beam epitaxy(MBE) and atomic layer epitaxy (ALE). They have the structure of formulaII:

    ML.sub.n ·pD                                      (II)

wherein

M is a metal chosen from the group consisting of: Li, Na, K, Rb, Cs, Mg,Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, Mo, W, Mn,Re, Sm, Fe, Ru, Eu, Os, Co, Rh, Ir, Gd, Ni, Pd, Pt, Tb, Cu, Ag, Au, Dy,Ho, Al, Ga, In, Tl, Er, Ge, Sn, Pb, Tm, Sb, Bi, Yb, and Lu;

D is a neutral coordinating ligand;

n is equal to the valence of M;

p is zero or an integer from 1 to 6; and

L is a ligand of formula III: ##STR14## wherein R¹ is alkyl, substitutedalkyl, haloalkyl, cycloalkyl, aryl, substituted aryl, heteroaryl,arylalkyl, alkoxy, acyl, alkyl carboxylate, aryl carboxylate, alkenyl,alkynyl, or E² (R⁶)(R⁷)(R⁸);

R² is H, halogen, nitro, or haloalkyl;

E¹ and E² are independently Si, Ge, Sn, or Pb;

R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently chosen from alkyl,substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl,alkoxy, alkenyl, alkynyl or R⁴ and R⁵, or R⁷ and R⁸ taken together forma divalent alkyl radical;

Y and Z are independently O, S or NR⁹ ; and

R⁹ is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.

Preferred metals are Cu, Co, Mn, Ag, In, Ce, Sr, Ba, Ru, or Au. Morepreferred metals are Cu and Ag. Preferred ligands are the preferredorganometalloid compounds described above. Ligands having reduced oxygencontent can reduce oxygen contamination of the substrate during metaldeposition. Preferred metal complexes are listed in Table 2:

                                      TABLE 2                                     __________________________________________________________________________    Cu((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.2                                            Cu(CF.sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                 Cu((CH.sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                                                    Cu((CH.sub.3).sub.2 CHCH.sub.2 COCHCOSi(CH.sub.3).sub.3)                      .sub.2                                                      Cu(CH.sub.3 CH.sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                            Cu(CF.sub.3 (CF.sub.2).sub.2 COCHCOSi(CH.sub.3).sub.3).s                      ub.2                                                        Cu(CH.sub.3 CH.sub.2 CH.sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                   Cu(C.sub.6 H.sub.5 COCHCOSi(CH.sub.3).sub.3).sub.2          Cu(CH.sub.3 (CH.sub.2).sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                                    Cu(H.sub.2 C═(CH.sub.3)COCHCOSi(CH.sub.3).sub.3).sub                      .2                                                          Cu((CH.sub.3).sub.2 CHCOCHCOSi(CH.sub.3).sub.3).sub.2                                           Co((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.3        Ag((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3)                                                  Mn((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.3        __________________________________________________________________________

The metal complexes of the present invention may contain one or moreneutral coordinating ligands (D in formula II) in addition to theorganometalloid ligands described above, in particular when the metalhas a valence of one. Suitable coordinating ligands include Lewis basessuch as vinyltrimethylsilane (VTMS), bis(trimethylsilyl) acetylene,1,5-cyclooctadiene (COD), 1,6-dimethyl-1,5-cyclooctadiene, alkylphosphines, alkynes and mixtures thereof

Synthetic methods for the preparation of β-diketones are numerous andwell documented. However, application of these strategies to thesynthesis of silyl β-diketonates is frequently unsuccessful, due to thereactivity of the product to the reagents or reaction conditions, and tothe occurrence of side reactions via the cleavage of thecarbonyl-silicon bond. Therefore, it is preferred that theorganometalloid compounds of the present invention be prepared by theprocesses of the present invention.

The organometalloid compounds may be prepared by a Claisen condensationbetween a lithium enolate and an acyl, thioacyl or imino compound havinga leaving group adjacent to the unsaturated group. This reaction isillustrated in Scheme 1:

SCHEME 1 ##STR15##

In Scheme 1, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, E¹, Y and Z are asdefined for the compounds of formula I, above, R is alkyl, and Q is aleaving group. Suitable leaving groups for the process are halo, acyl,alkoxy, phenoxy, amido, dialkylamino and alkoxyamino. Preferably, R¹C(Y)Q is an acid chloride or an ester.

In another embodiment, the organometalloid compounds are prepared asillustrated in Scheme 2. A thioketal-protected acylmetalloid is reactedwith an alkyllithium compound, such as n-butyl lithium, and the productis subsequently reacted with a copper salt to form a protected lithiumdithianylmetalloid cuprate. The cuprate is then reacted with anappropriate α-bromoketone or α-bromothioketone. The thioketal protectinggroup can be removed by methods described in the literature. Preferablythe deprotection is accomplished by treatment with a suitable mercuryreagent. An example of an effective mercury reagent is a combination ofmercuric oxide and mercuric chloride.

SCHEME 2 ##STR16##

The metal complexes of the present invention may be prepared by reactingthe organometalloid compounds synthesized as described above with ametal salt under protic or aprotic conditions. The ligand is dissolvedin a suitable solvent and the anion of the ligand is formed byabstraction of a proton with base. The metal salt is then added, and theresulting metal ligand complex is isolated by removal of the solvent andcrystallized. Under protic conditions, a protic base such as sodiumhydroxide, may be used, with a protic solvent, such as an aqueousalcohol. Similarly under aprotic conditions, aprotic bases and solventsmay be used. An example of a suitable aprotic solvent istetrahydrofuran; an example of a suitable aprotic base is potassiumhydride.

In another embodiment, the metal complexes may be prepared directly asshown in Scheme 3.

SCHEME 3 ##STR17##

In Scheme 3, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, E¹, Y and Z are asdefined for the compounds of formula I, above, and R is alkyl or phenyl.The starting lithium metalloid compound of formula E¹ R³ R⁴ R⁵ Li isprepared according to the method described in the literature, (Still, W.C., J. Org. Chem. 41, 3063-3064 (1976)). The lithiummetalloid compoundis then reacted with an appropriate compound, for example, a β-diketone,a β-thioketone, or a β-keto-imine, to yield a ligand of formula I.Without isolating the product, a metal salt is added to form a complexof the metal with the ligand.

Processes whereby metals are deposited from volatile precursors areutilized in many different microelectronics applications. Metals such asLi, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, or Ce are typically usedin applications such as high k dielectrics, superconductors, and highrefractive index materials, although their use is not limited to theseapplications. Metals such as Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, Mo, W,Mn, Re, or Sm are typically used in microelectronic applicationschemically combined with nitrogen or silicon as the nitride or silicidefor use as barrier materials or hard coatings, although, again, theiruse is not limited to these applications. Metals such as Fe, Ru, Eu, Os,Co, Rh, Ir, Gd, Ni, Pd, Pt, Tb, Cu, Ag, Au, Dy, Zn, Cd, Hg, Ho, Al, Ga,In, Tl, and Er are typically used in electronics applications as metals,or metal alloys, in particular, as metal or metal alloy films forinterconnects, electrodes, and mirrors, although, again, their use isnot limited to these applications. Metals and metalloids such as Si, Ge,Sn, Pb, Tm, Sb, Bi, Yb, and Lu are typically used in microelectronicdevices and as semiconductors, although, again, their use is not limitedto these applications.

The metal complexes of the present invention may be deposited on asubstrate to form a layer of one or more metals in the form of the metalor of particular inorganic compounds, for example as an oxide, ahydroxide, a carbonate or a nitride. It will be apparent to a personskilled in the art that, if desired, he may use not only a particularcompound of formula II but also mixtures of such compounds in which M,L, or both vary. A metal complex is advantageously decomposed in thevapor phase by a metal organic chemical vapor deposition (MOCVD),molecular beam epitaxy (MBE) or atomic layer epitaxy (ALE) process. Theprinciple of these processes and suitable apparatuses for these purposesare well known in the art.

Typically, an apparatus for deposition from the vapor phase is pressuretight and can be evacuated. The substrate which is to be coated is to beintroduced into this apparatus. Under reduced pressure the complex offormula II is vaporized. If desired, inert or reactive gas may bepresent in the apparatus in addition to the complex of the presentinvention in the vapor state.

The metal complex, in vapor form, is typically continuously orintermittently introduced into the apparatus via a special line. In somecases the metal complex may be introduced into the apparatus togetherwith the substrate which is to be coated and not vaporized until it iswithin the apparatus. A carrier gas may optionally be used to aid intransporting the metal complex into the apparatus. The vaporization ofthe metal complex can be promoted by heating and if desired by theaddition of the carrier gas.

Decomposition of the substrate may be effected by known methods. Ingeneral, these are thermal decomposition, plasma-or radiation-induceddecomposition and/or photolytic decomposition.

Thermal decomposition from the vapor phase is usually performed so thatthe walls of the apparatus are kept cold and the substrate is heated toa temperature at which the desired layer is deposited on the substrate.The minimum temperature required for decomposition of the compound maybe determined in each case by simple testing. Usually, the temperatureto which the substrate is heated is above about 80° C.

The substrate may be heated in a conventional manner, for example, byresistance heating, inductive heating, or electric heating, or thesubstrates may be heated by radiation energy. Laser energy isparticularly suitable for this. Laser heating is particularlyadvantageous in that lasers can be focused, and therefore canspecifically heat limited areas on the substrate.

An apparatus for thermal chemical vapor deposition is typically pressuretight such as are used in high vacuum techniques as this process istypically carried out under reduced pressure. The apparatus may comprisegas lines which can be heated for carrying the metal complexes or theinner gas, blockable gas inlets and outlets, temperature measuring meansif decomposition is to be induced by radiation, a radiation source mustalso be present.

In operation, the metal complex is introduced into the apparatus in thevapor phase. An inert or reactive carrier gas may be included.

Decomposition of the metal complex may be brought about as discussedabove. For example, the decomposition may be plasma induced by a D.C.plasma, high-frequency plasma, microwave plasma or glow dischargeplasma. Alternately photolytic decomposition may be effected by using alaser operating at a suitable wavelength.

The thickness of the layer deposited typically depends on the length ofthe deposition, on the partial pressure in the gas phase, on the flowrate of the gas and on the decomposition temperature. Depending on thedesired layer thickness, a person skilled in the art can readilydetermine the time and deposition temperature required to produce alayer of a given thickness by simple tests.

If the metal complex is decomposed under an atmosphere of an inert gas,for example, argon, metal-containing layers are typically deposited inwhich the metal is in essentially metallic form. The decomposition mayalso be carried out under a reactive gas atmosphere, including areducing atmosphere, an oxidizing atmosphere, and a hydrolyzing orcarbonizing atmosphere. A reducing atmosphere with hydrogen as thereactive gas is typically used for deposition of layers containingmetals, for example, copper metal. Where the decomposition is carriedout under an oxidizing atmosphere, for example, one containing oxygen,nitrogen dioxide or ozone, layers containing the metal in the form of anoxide are formed. Alternatively, it is also possible to operate in ahydrolyzing or carbonizing atmosphere, for instance, in the presence ofwater and/or carbon dioxide. The metal carbonate or hydroxide which isproduced as an intermediate stage may be subsequently calcined to formthe metal oxide. In addition, use of ammonia as a reactive gas yieldslayers containing the metal in the form of a nitride.

The process according to the invention is also suitable for depositinglayers which contain one or more metals. In this case, the depositionprocess is characterized in that for depositing layers containing morethan one metal, one or more compounds of formula II or other formulasare decomposed simultaneously or successively.

EXAMPLES Example 1

Preparation of (CH₃)₃ CCOCH₂ COSi(CH₃)₃ (IV) via Claisen Condensation ofa Lithium Enolate and an Acid Chloride.

A two liter 3-neck flask held at 0° -C. was equipped with a magneticstirrer, a rubber septum and a silicon oil bubbler under a positive flowof nitrogen gas. The flask was charged with anhydrous diethyl ether (250mL) and diisopropylamine, (11.3 mL, 86.2 mmol), 2.5 M solution of n-BuLiin hexane (34.5 mL, 86.2 mmol) was added very slowly to the stirredsolution. Once addition of the n-BuLi was complete the reactiontemperature was maintained at 0° C. for 1 h to ensure generation oflithium diisopropylamide, (LDA). The temperature was lowered to -85° C.and acetyltrimethylsilane (10.0 g, 86.2 mmol), was then added slowly tothe mixture. A smooth exothermic reaction ensued which resulted in theformation of corresponding organolithium anion, (Me₃ Si(C)(OLi)CH₂). Asecond one liter single-neck flask held at -110° C. equipped with amagnetic stirrer, a rubber septum and under a positive flow of nitrogengas, was charged with anhydrous diethyl ether (250 mL) andtrimethylacetylchloride, (10.6 mL, 86.2 mmol). After 10 minutes thelabile trimethylsilylorganolithium anion, (Me₃ Si(C)(OLi)CH₂), wasslowly transferred to the second flask via a cannula the reactiontemperature was maintained between -110° C. and -75° C. After 1 hour,the reaction was essentially complete and was quenched with saturatedammonium chloride solution. Purification of the silyl β-diketonate waseffected via flash column chromatography using a 100:1 (hexane: diethylether) eluant.

Example 2

Preparation of IV via Claisen Condensation of a Lithium Enolate and anEster.

A two liter 3-neck flask held at 0° C. equipped with a magnetic stirrer,a rubber septum and a silicon oil bubbler and under a positive flow ofnitrogen gas was charged with anhydrous diethyl ether (250 mL) anddiisopropylamine, (11.3 mL, 86.2 mmol). n-Butyllithium (34.4 mL, 86.2mmol, 2.5 M in hexane) was added very slowly to the stirred solution.Once addition of the n-BuLi was complete, the reaction temperature wasmaintained at 0° C. for 1 hour to ensure generation of lithiumdiisopropylamide, (LDA). The temperature was then lowered to -85° C. andacetyltrimethylsilane (10.0 g, 86.2 mmol) was added slowly to themixture. A smooth exothermic reaction ensued which resulted in theformation of corresponding lithium enolate, (Me₃ Si(C)(OLi)CH₂). Asecond one -liter single-neck flask held at -110° C. equipped with amagnetic stirrer, a rubber septum and under a positive flow of nitrogengas, was charged with anhydrous diethyl ether (250 mL) and methylpivaloate, (10.6 mL, 86.2 mmol). After 10 minutes, the reactive lithiumenolate, (Me₃ Si(C)(OLi)CH₂), was slowly transferred to this mixture viaa cannula while the reaction temperature was maintained between -110° C.and -75° C. After 2 hours, the reaction was essentially complete and wasthen quenched with saturated ammonium chloride solution. Purification ofthe silyl β-diketonate was effected via flash column chromatographyusing a 100:1 (hexane:diethyl ether) solvent system.

Example 3

Preparation of IV via Pseudo Barbier Conditions.

Trimethylsilyllithium, (18 mmol) was prepared according to theliterature method (Still, W. C., J. Org. Chem., 41, 3063-3064 (1976))and then transferred via cannula to a second reaction flask held at -78°C., charged with anhydrous diethyl ether, (150 mL) and methyl4,4-dimethyl-3-oxopentanoate, (CH₃)₃ CCOCH₂ CO₂ CH₃ (2.09g, 18 mmol),which resulted in the dissipation of the red colour. (Gasking, E. I.;Whitman, G. H. J. Chem. Soc., Perkin Trans. 1, 1985, 409-414) After 30minutes the reaction was quenched with saturated ammonium chloride, (100mL) and copper acetate (II) monohydrate, (3.60g, 18 mmol) was added toyield the crude silyl β-diketonate copper complex. Subsequentpurification yielded pure metal complex.

Example 4

Preparation of IV by the Dithiane Route.

A 3-neck flask held at -30° C. was equipped with a magnetic stirrer, arubber septum and a silicon oil bubbler was under a positive flow ofnitrogen gas. The flask was charged with anhydrous THF (30 mL) and2-trimethylsilane-1,3-dithiane, (3.8 mL, (20 mmol). n-Butyllithium (8.0mL, 20 mmol, 2.5 M in hexane) was added very slowly to the stirredsolution. Once addition of n-BuLi was complete the reaction temperaturewas maintained at -30° C. for 24 hour to ensure generation of2-lithio-1,3 dithiane. The anion was transferred via a cannula to asecond flask maintained at -60° C. and charged with an ethereal solutionof CuBr·Me₂ S (2.06 g, 10 mmol). After approximately one hour theformation of the 2-lithio-1,3-dithianylcuprate was essentially complete.Bromo pinacolone, (CH₃)₃ CCOCH₂ Br, dissolved in ether, was then addedslowly to the organocuprate and was allowed to react for 24 hour at -30°C. The reaction was quenched with saturated ammonium chloride solution.Vacuum distillation (125-130° C., 0.5 mm Hg) afforded the pure product.

Deprotection of the dithiane protected silyl β-diketonate was achievedby treatment with mercuric oxide and mercuric chloride in an aqueousalcoholic solution for 1.5 hours, yielding the desired the silylβ-diketonate upon filtration and concentration.

Example 5

Formation of Co((CH₃)₃ CCOCHCOSi(CH₃)₃)₃ under Protic Conditions.

A solution of IV (0.54 g, 2.7 mmol) prepared as in Example 1 in aqueousethanol (80 mL) was prepared. To the stirred solution, an aqueousethanolic solution of sodium hydroxide (0.1 g, 3 mmol) was slowly addedand allowed to react approximately 15 minutes. The slow addition of thissolution to cobalt (II) chloride hexahydrate, (0.30 g, 1.4 mmol)dissolved in aqueous ethanol resulted in the formation of a deep greensolution. The solvent was removed in vacuo to leave behind the crudecobalt (III)silyl β-diketonate complex. Addition of pentane and water,followed by subsequent work-up and sublimation resulted in isolation ofthe analytically pure metal complex.

Example 6

Formation of Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂ under Aprotic Conditions.

Under aprotic conditions, IV (0.25 g, 1.3 mmol), prepared as in Example1, was dissolved in THF (100 mL). To the stirred solution, potassiumhydride, (KH), (0.05 g, 1 mmol) was added slowly and allowed to reactfor approximately 30 minutes. The addition of copper (II) chloridedihydrate, (0.11 g, 6.3 mmol) portionwise resulted in the formation of adeep green solution. The reaction was then quenched carefully with waterand extracted with pentane. The solvent was then removed in vacuo toleave behind the copper (II) silyl β-diketonate complex, which onsublimation yielded the analytically pure metal complex.

Example 7

Formation of Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂ under Protic Conditions.

Under protic conditions, IV (0.25 g, 1.3 mmol), prepared as in Example1, was dissolved in aqueous ethanol (80 mL). To the stirred solution, anaqueous ethanolic solution of sodium hydroxide (0.1 g, 3 mmol) wasslowly added and allowed to react approximately 15 minutes. Copper (II)chloride dihydrate, (0.11 g, 6.3 mmol) was then added which resulted inthe formation of a deep green solution. The solvent was then removed invacuo to leave behind the copper (II) silyl β-diketonate complex.Sublimation resulted in the isolation of analytically pure metalcomplex.

Example 8

Direct Formation of Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂ using Crude IV

To a stirred solution of crude IV (2.73g, 13.8 mmol) dissolved in THF(100 mL), a slurry of excess copper (II) acetate hydrate, (5.46 g, 27.4mmol) in aqueous THF was added. Upon addition, a deep green solutionformed. Extraction, washing, drying, and concentration resulted inisolation of a green oil. Column chromatography on silica gel using a100:1 hexane-ether eluant system yielded semi-pure copper (II) silylβ-diketonate complex. Controlled sublimation resulted in the formationof analytically pure metal complex.

Example 9

Direct Formation of Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂ using Pure IV

To a stirred solution of pure IV, (5.00 g, 25 mmol) dissolved in THF(100 mL), a slurry of copper (II) acetate hydrate, (3.00 g, 15 mmol) inaqueous THF was added. Upon addition, a deep green solution formed.Extraction, washing, drying, and concentration in vacuo resulted inisolation of the copper (II) silyl β-diketonate complex. Sublimationresulted in the formation of analytically pure metal complex.

Example 10

Preparation of Cu(I)((CH₃)₃ CCOCHCOSi(CH₃)₃)·COD

Under anaerobic conditions, 1,5-cyclooctadiene (0.1 g, 1 mmol) was addeddropwise to a suspension of copper (I) chloride in THF. The suspensionwas stirred for 10 minutes, after which a solution of the potassium saltof IV (prepared by the addition of potassium hydride (0.05 g, 1 mmol)over 30 minutes to a solution of IV (0.25 g, 1.3 mmol)), was carefullyadded via syringe and allowed to react for approximately 3 hours. Theresultant copper(I) silyl β-diketonate complex was isolated bysubsequent anhydrous work-up.

Example 11

Formation of Mn((CH₃)₃ CCOCHCOSi(CH₃)₃)₃ via Lewis Base.

A solution of IV (0.54 g, 2.7 mmol) in aqueous ethanol (80 mL) wasprepared. To the stirred solution was slowly added an aqueous ethanolicsolution of sodium hydroxide (0.1 g, 3 mmol). The resultant solution wasstirred for approximately 15 minutes and then slowly added to manganese(II) chloride (0.176 g, 1.4 mmol) dissolved in aqueous ethanol whichresulted in the formation of a dark green solution. The solvent wasremoved in vacuo to leave behind the crude manganese (III) silylβ-diketonate complex. Addition of pentane and water followed bysubsequent work-up and sublimation yielded an analytically pure metalcomplex.

Example 12

Preparation of Cu((CH₃)₃ CCSCHCOSi(CH₃)₃)₂ via Claisen Condensation ofLithium Enolate and Thioacid Chloride.

A two liter 3-neck flask held at 0° C. was equipped with a magneticstirrer, a rubber septum and a silicon oil bubbler under a positive flowof nitrogen gas. The flask was charged with anhydrous diethyl ether (250mL) and diisopropylamine (11.3 mL, 86.2 mmol). n-Butyllithium (34.5 mLof a 2.5 M solution in hexane, 86.2 mmol) was added very slowly to thestirred solution. Once the addition of BuLi was complete, the reactiontemperature was held at 0° C. for 1 hour to ensure generation of lithiumdiisopropylamide, (LDA). The temperature was lowered to -85° C. andacetyltrimethylsilane (10.0 g, 86.2 mmol) was added slowly to themixture. A smooth exothermic reaction ensued which resulted in theformation of corresponding organolithium enolate, (Me₃ Si(C)(OLi)CH₂). Asecond one liter single-neck flask held at -110° C. and equipped with amagnetic stirrer, a rubber septum under a positive flow of nitrogen gas,was charged with anhydrous diethyl ether (250 mL) andtrimethylthioacetylchloride, (10.6 mL, 86.2 mmol). After 10 minutes, thelabile trimethylsilylorganolithium anion, (Me₃ Si(C)(OLi)CH₂), wasslowly transferred to the second flask via cannula while maintaining thereaction temperature between -110° C. and -75° C. After 1 hour thereaction was quenched with saturated ammonium chloride solution.Purification of the β-thioketoacyl-silane can be effected by flashcolumn chromatography using a 100:1 (hexane:diethyl ether) eluant. Theproton NMR spectrum of the product gave the expected results.

Example 13

Volatility of Metal Complexes with Silyl β-diketonates and Silylβ-thioketonates

Thermogravimetric analysis (TGA) was performed on samples of the metalcomplexes listed in Table 3. The samples were heated at a rate of 10°C./min under an argon atmosphere. Weight loss was associated withtransformation of the complexes into the vapor phase. The TGA curvesshowed rapid and complete volatilization of the complexes over a narrowtemperature range, indicating the absence of decomposition under theconditions employed. The temperature at which 50% of the sample, byweight, has volatilized (T_(50%)) is a measure of relative volatility,and is listed in the table for each compound. The T_(50%) values rangefrom a low of about 111° C. for the fluorinated compound Cu(CF₃COCHCOSi(CH₃)₃)₂, to a high of about 170° C. for a complex with aphenyl-substituted ligand, Cu(C₆ H₅ COCHCOSi(CH₃)₃)₂.

                  TABLE 3                                                         ______________________________________                                        Volatility of Metal Diketonate Complexes                                      Metal Complex         T.sub.50%, ° C.                                  ______________________________________                                        Cu((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.2                                                158                                                     Co((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.3                                                167                                                     Mn((CH.sub.3).sub.3 CCOCHCOSi(CH.sub.3).sub.3).sub.3                                                119                                                     Cu((CH.sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                                                        155                                                     Cu(CH.sub.3 CH.sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                                150                                                     Cu(CH.sub.3 CH.sub.2 CH.sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                       152                                                     Cu(CH.sub.3 (CH.sub.2).sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                                        158                                                     Cu((CH.sub.3).sub.2 CHCOCHCOSi(CH.sub.3).sub.3).sub.2                                               137                                                     Cu((CH.sub.3).sub.2 CHCH.sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                      161                                                     Cu(CF.sub.3 COCHCOSi(CH.sub.3).sub.3).sub.2                                                         111                                                     Cu(CF.sub.3 (CF.sub.2).sub.2 COCHCOSi(CH.sub.3).sub.3).sub.2                                        120                                                     Cu(C.sub.6 H.sub.5 COCHCOSi(CH.sub.3).sub.3).sub.2                                                  170                                                     Cu(H.sub.2 C═(CH.sub.3)COCHCOSi(CH.sub.3).sub.3).sub.2                                          134, 234                                                ______________________________________                                    

Example 14

Chemical Vapor Deposition of Copper

Copper films were deposited on fragments of silicon wafers, includingwafers having surfaces composed of silicon, silicon dioxide, patternedsilicon dioxide, and tungsten nitride, using a copper (II) silylβ-diketonate precursor of composition Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂.

A cold wall stainless steel single wafer CVD reactor was employed forthe depositions. The wafers were loaded into the chamber through a doorand placed on a resistively heated stainless steel pedestal bearing aquartz plate and heated to 300° C. under a flowing hydrogen ambientatmosphere. The actual temperature of the wafer was measured via athermocouple contacting the top side of the wafer. The system pressurewas then reduced to the desired deposition pressure of 500 mTorr. Thepressure was maintained throughout the time of the deposition using anautomated throttle valve.

A source of the precursor was maintained at 140° C. The precursor wasdelivered to the reactor by means of a hydrogen carrier/reactant gasbubbler at a flow rate of 60 sccm at approximately 500 mTorr . After thedeposition, the carrier gas flow was terminated, the source was closedto the reactor, and the chamber was evacuated to less than 20 mTorr andthen flushed with nitrogen gas. The heater was allowed to cool under aflow of nitrogen. The test wafers were retrieved from the reactorthrough the door of the reactor.

The resulting copper films were smooth and exhibited high conformalityat thicknesses ranging from 100 Å to 3000 Å (10 nm to 300 nm).

What is claimed:
 1. A method of depositing a metal-containing layer on asubstrate comprising:(a) vaporizing a metal-ligand complex of formula II

    ML.sub.n ·pD                                      (II)

wherein M is a metal selected from the group consisting of: Li, Na, K,Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd,Cr, Mo, W, Mn, Re, Sm, Fe, Ru, Eu, Os, Co, Rh, Ir, Gd, Ni, Pd, Pt, Tb,Cu, Ag, Au, Dy, Ho, Al, Ga, In, Tl, Er, Ge, Sn, Pb, Tm, Sb, Bi, Yb, andLu; D is a neutral coordinating ligand; n is equal to the valence of M;p is zero or an integer from 1 to 6; and L is a ligand of formula III:##STR18## wherein R¹ is alkyl, substituted alkyl, haloalkyl, cycloalkyl,aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, acyl, alkylcarboxylate, aryl carboxylate, alkenyl, alkynyl, or E² (R⁶)(R⁷)(R⁸); R²is H, halogen, nitro, or haloalkyl; E¹ and E² are independently Si, Ge,Sn, or Pb; R³, R⁴, R⁵, R⁶, R⁷, and R⁸ are independently selected fromalkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl,alkoxy, alkenyl, alkynyl or R⁴ and R⁵, or R⁷ and R⁸ taken together forma divalent alkyl radical; Y and Z are independently O, S or NR⁹ ; and R⁹is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl,heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl; and (b) decomposingthe metal-ligand complex in the presence of the substrate.
 2. A methodaccording to claim 1, whereinR¹ is alkyl, aryl or haloalkyl; R² is H; R⁴is methyl; E¹ is Si; and Y and Z are independently O or S.
 3. A methodaccording to claim 2, whereinR¹ is ethyl, isopropyl, n-propyl, isobutyl,n-butyl, t-butyl, trifluoromethyl, heptafluoropropyl, 2-propenyl orphenyl; R² is H; R⁴ is methyl; E¹ is Si; and Y and Z are O or Y is S andZ is O.
 4. A method according to claim 1, wherein M is Li, Na, K, Rb,Cs, Mg, Ca, Sr, Ba, Sc, Y, La, or Ce.
 5. A method according to claim 1,wherein M is Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, Mo, W, Mn, Re, or Sm. 6.A method according to claim 1, wherein M is Fe, Ru, Eu, Os, Co, Rh, Ir,Gd, Ni, Pd, Pt, Tb, Cu, Ag, Au, Dy, Zn, Cd, Hg, Ho, Al, Ga, In, Tl, orEr.
 7. A method according to claim 1, wherein M is Si, Ge, Sn, Pb, Tm,Sb, Bi, Yb, Lu, Th or U.
 8. A method according to claim 6, wherein M isCu.
 9. A method according to claim 8, wherein the metal-ligand complexcomprises Cu((CH₃)₃ CCOCHCOSi(CH₃)₃)₂.
 10. A method according to claim8, wherein the metal-ligand complex comprises Cu((CH₃ COCHCOSi(CH₃)₃)₂.11. A method according to claim 8, wherein the metal-ligand complexcomprises Cu(CH₃ CH₂ COCHCOSi(CH₃)₃)₂.
 12. A method according to claim8, wherein the metal-ligand complex comprises Cu(CH₃ CH₂ CH₂COCHCOSi(CH₃)₃)₂.
 13. A method according to claim 8, wherein themetal-ligand complex comprises Cu(CH₃ (CH₂)₃ COCHCOSi(CH₃)₃)₂.
 14. Amethod according to claim 8, wherein the metal-ligand complex comprisesCu((CH₃)₂ CHCOCHCOSi(CH₃)₃)₂.
 15. A method according to claim 8, whereinthe metal-ligand complex comprises Cu((CH₃)₂ CHCH₂ COCHCOSi(CH₃)₃)₂. 16.A method according to claim 8, wherein the metal-ligand complexcomprises Cu(CF₃ COCHCOSi(CH₃)₃)₂.
 17. A method according to claim 8,wherein the metal-ligand complex comprises Cu(CF₃ (CF₂)₂COCHCOSi(CH₃)₃)₂.
 18. A method according to claim 8, wherein themetal-ligand complex comprises Cu(C₆ H₅ COCHCOSi(CH₃)₃)₂.
 19. A methodaccording to claim 8, wherein the metal-ligand complex comprises Cu(H₂C═C(CH₃)COCHCOSi(CH₃)₃)₂.
 20. A method according to claim 6, wherein Mis Co.
 21. A method according to claim 20, wherein the metal-ligandcomplex comprises Co((CH₃)₃ CCOCHCOSi(CH₃)₃)₃.
 22. A method according toclaim 5, wherein M is Mn.
 23. A method according to claim 20, whereinthe metal-ligand complex comprises Mn((CH₃)₃ CCOCHCOSi(CH₃)₃)₃.
 24. Amethod according to claim 6, wherein M is Ag.
 25. A method according toclaim 24, wherein the metal-ligand complex comprises Ag((CH₃)₃CCOCHCOSi(CH₃)₃).